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Corrosion is a serious problem that affects and undermines the quality of everyday social life and the endurance of industrial products. Extensive efforts have been undertaken to design and fabricate products such as steam generators, heat exchangers, bridges, oil drilling platforms and motor vehicles that can resist the destructive effects of corrosion. For many traditional products, however, corrosion continues to be a serious destructive problem. In addition to traditional products, new developments in energy sources, advances in material sciences, microprocessing technology and miniaturization of new devices to the micron scale all reassert the demands for effective anti-corrosion technologies that avert device failures.
Corrosion is typically understood as an electrochemical reaction that involves loss of electrons from metals, a reaction more generally described as oxidation. The definition of oxidation in electrochemical terms is independent of whether or not oxygen is present when the process of electron loss from a metal occurs. The loss of one or more electrons from a metal requires the acquisition of the electron(s) by another agent. Thus, the metal that serves as an electron donor in this case is termed a reducing agent, while the electron acceptor serves as an oxidizing agent. One practical example illustrating such an electrochemical event typically involves metallic iron. Electrons lost from an iron atom (reducing agent) can be acquired by oxygen (oxidizing agent) to produce a new combined iron and oxygen derivative identified as iron oxide, or rust, which is an inorganic, low density (flaky) product commonly associated with metal corrosion. Although oxygen is used as a model of iron oxidation in this case, the same oxidizing agent effect could be demonstrated by sulfur and the resulting product could have been iron sulfide instead of iron oxide.
Apart from rust involving metal corrosion, the formation of scale presents another illustrative model tied to principles of oxidation. Scale is defined as a thin coating, layer or encrustation of material that is rich in complex oxides of sulfur, magnesium and/or calcium. These and other insoluble materials are typically developed and observed as mineral deposits on the inside diameters of pipes, chambers or containment vessels when water plus its dissolved constituents. or solutes, are heated in the process of making hot water.
The transfer of electrons between oxidizing agents and reducing agents cannot occur without the presence of an electrically conductive medium. Water typically serves as the electrically conductive universal solvent medium that supports metal oxidation, consequential corrosion and rusting as well as scale formation in the foregoing models.
Efforts to halt water-mediated metal oxidation and corrosion typically rely on superficial passivation of the metal with toxic materials such as chromic acid, sacrificial coatings (e.g., zinc or galvanized coatings), electroplated metals, polymeric coatings or related efforts that produce a protective barrier between the reactive metal surface and water. Implementation of such strategies usually produces an inflexible anti-corrosion barrier on metal surfaces, and once applied, its removal may be difficult or impossible. For those situations where micro-mechanical or circuit-based devices display corrosion tendencies, aggressive industrial anti-corrosion methods may be totally unsuitable and physically damaging. Thus, there is a significant need for new, simple-to-execute anti-corrosion barrier possibilities.
The invention described herein is directed to preventing the oxidative corrosion of metal surfaces. The invention relies on the exposure of a metal surface to an anti-corrosion agent characterized as 2,4-trans, trans-hexadienoic acid (2,4-HDA), its alkali salt identified as potassium sorbate (KHDA), or other derivatives that conserve or embody the 2,4-trans, trans-hexadiene-type moiety present in their molecular structures, as an active anti-corrosion agent (ACA) in combination with a material, as hereinafter defined, capable of forming a moisture retentive barrier on the surface of the metal. In certain applications, the anti-corrosion agent alone is sufficient to achieve the desired anti-corrosive effect.
In preferred embodiments, the material capable of forming a moisture retentive barrier film over a surface of the metal is selected from the group consisting of a polar liquid, a non-polar liquid, a viscous material, an organic liquid, a polymeric material and a petroleum-based substance; and the composition further comprises any one of a polar liquid, a non-polar liquid, a surfactant, an antioxidant, an organic liquid, a polymeric material, a petroleum-based substance, a buffering material, or graphite or particulate carbon in a suspension. The anti-corrosion agent in the composition of the invention may be packaged for delayed release, e.g., by encapsulation. Preferably, the anti-corrosion agent is present in the composition at a concentration of between 0.2 and 58 percent by weight. Most preferably, the composition is first prepared in concentrated form and then diluted prior to use. The anti-corrosion agent spontaneously adsorbs or chelates to metal surfaces from water solutions so as to produce an organometallic barrier coating. In addition, the residual anti-corrosion agent, after having had an opportunity to adsorb to the metal surface, remains as an aqueous solution where it effectively alters the normal dielectric properties of available water that could contribute to the water""s ordinary corrosion properties.
The compositions and methods of the invention provide a practical, non-toxic way of ensuring anti-corrosion protection for metals, or devices containing exposed metals, stored or operated in water or in the presence of water vapor. Exemplary, non-inclusive uses include employing the composition as a lubricant for the surface of a metal or as a pump oil or brake fluid; using the composition as an undercoating for painting, electro-plating or electro-polishing procedures; and providing a protective coating for any metal or metal-containing machine or device, from automotive assembly plant metal press machines to electronic circuit boards.
The present invention is directed to the use of 2,4-trans, trans-hexadienoic acid (HDA or sorbic acid), KHDA (a potassium salt of sorbic acid), or their derivatives that structurally conserve the characteristic 2,4-trans, trans-diene moiety as an active anti-corrosion agent (ACA), in combination with a material, as hereinafter defined, chosen, e.g., for its low dielectric constant (D-value) and/or for its lubrication properties and capable of forming a moisture retentive barrier to provide anti-corrosion protection for metal surfaces. In certain applications, e.g., if the protected metal object remains immersed in a KHDA solution, the anti-corrosion agent alone is sufficient to achieve the desired anti-corrosive effect. However, most preferably, the anti-corrosion agent is used in combination with a material capable of forming a moisture retentive barrier on the surface of the article to be protected. This composition not only achieves superior results during immersion but also permits the protected article to be dried and to still retain long term anti-corrosion protection.
The invention disclosed here provides a practical, non-toxic method that ensures anti-corrosion protection for metals, or devices containing exposed metals, stored or operated in water or in the presence of water vapor. Preparations of 2,4-trans, trans-hexadienoic acid (HDA) present as its potassium salt (KHDA), hereinafter designated as the active anti-corrosion agent (ACA), will inhibit the corrosion of metals for indefinite periods of time in a variety of venues as hereinafter described, e.g., while the metals remain immersed in a KHDA-solution, following coating with KHDA in combination with other viscous agents or otherwise jacketed in KHDA by a moisture retentive barrier.
KHDA, as the potassium salt of HDA, dissociates in water to give the 2,4-trans, trans-hexadienoic anion plus a stoichiometrically molar equivalent concentration of potassium ions. The anion provided by the dissociation of KHDA in water is equivalent in structure and function to the anion produced upon the ionization of HDA in water according to principles of weak acid behavior as dictated by its ionization constant (Keq). Although the method of the invention may be implemented by dissolving KHDA in water as an expeditious route for providing the ACA activity, Ache functional ACA activity is due to the 2,4-trans, trans-hexadienoic anion. Thus, any substance that directly or indirectly yields this functional anion or provides for its time-released potential availability to any system that contains or might acquire water is considered to be a functional 2,4-trans, trans-hexadiene moiety of the invention and will have equivalent anti-corrosion consequences. This includes the possible embodiment of the anion or its equivalent as (1) a covalently bonded moiety to any other single molecule; (2) a hydrolyzable acyl-ester of mono- or polyhydroxy alcohols as well as aldose and ketose sugars, their monosaccharidic acid equivalents and their polymers; (3) a hydrolyzable acyl-ester of a synthetic polymer or (4) as a hydrolyzable or nonhydrolyzable substituent of simple, complex or derived lipids. Structural modifications of the 2,4-trans, trans-hexadienoic acid where the carboxyl group (xe2x80x94COOH) is substituted or replaced by any other acidic groups, such as (xe2x80x94SO3H2) or (xe2x80x94PO3H2) but not to the exclusion of others, are also considered under the functional aegis of a 2,4-trans, trans-hexadienoic anion.
In addition to the use of a separate moisture retentive barrier, the KHDA-metal surface interaction can be ensured by incorporating the ACA into coatings such as those modeled by high viscosity water-soluble non-ionic barrier coatings applied by immersion (dipping) or spraying. While ensuring ACA contact and effectiveness over the surface of a metal, such barriers can be effectively removed by water when necessary, the unoxidized and uncorroded metal surface may be dried, and then further processed as desired. In other applications, for example, direct current may be applied surrounding the ACA-coated metal to produce a directed walk of the ACA away from the metal thereby leaving its surface relatively unprotected to corrosion.
A metal surface coated with an anti-corrosive barrier according to the invention is an excellent candidate for further coating, e.g., by painting or plating over, using fewer steps than are required with prior art processes, as shown in Example IX. In addition, less of the coating/plating material is required than with prior art methods to achieve a stronger, longer lasting barrier finish with no oxidation Furthermore, the coating material is less brittle when applied over an undercoating according to the invention. The composition of the invention may also be mixed into, e.g., a paint or epoxy material, which is then applied as desired, and the resulting coating is more pliable.
In place of water, solvents compatible with the dissolution of either or both the ACA or the chemically unrelated barrier coating can be used to rinse the substances from a treated metal surface. Such solvents could include organics, organic-water combinations with or without pH adjusted and ionic strength regulated buffer solutions.
The metal anti-corrosion protection mechanism for KHDA involves two uniquely independent effects that collaterally support the demonstrated anti-corrosion phenomenon. First, the ACA spontaneously adsorbs or chelates to metal surfaces from water solutions so as to produce an organometallic barrier. Secondly, the residual ACA in solution, after having had an opportunity to adsorb to the metal surface, remains as an aqueous solution where it effectively alters the normal dielectric properties of available water that could contribute to its ordinary corrosion properties. The molecular nature of the ACA is inherently responsible for these two effects, and neither of these effects can be made separable from the other as long as the molecule remains intact.
KHDA thus separates the metal surface from the water and blocks its contact with substances in solution that will promote surface metal oxidation and ensure evidence of corrosion. Compounds ordinarily implicated in corrosive mechanisms involve Group VIA elements of the Periodic Table, but not to the exclusion of others. Metal oxidation and corrosion rely on water-mediated electron transport plus oxidizing and reducing agent interactions. In the method of the invention, the required participation of water for electron transport does not occur. Accordingly, electron transfers mediated by water between materials with galvanically driven electrochemical potential differences can also be minimized.
Water effectively mediates electron flow between oxidizing and reducing agent (redox) pairs because it demonstrates a naturally occurring high dielectric constant (D) of 78.5. While not being bound by any theory, it appears that the demonstrated dielectric property of water is so affected by addition of the anti-corrosion agent of the invention that electrical devices protected according to the method of the invention can continue to be operated by alternating currents while the circuitry is immersed in water. Whether such a demonstration of lowered conductivity is applied to allowing a light bulb to luminesce with 110 volt alternating current supplied by uninsulated copper wires under water, or to reducing the electrochemical flux of electrons accountable for metal corrosion, the performance of the anti-corrosion agent of the invention is clear, defined and repeatable.
The decisive establishment of minimal effective ACA solution concentrations that will protect metals from surface corrosion is a common consideration. Although solutions of the ACA up to 58 percent by weight in water may allow indefinite metal resistance to oxidation and corrosion, much lower concentrations can be used in practice of the invention. Not being bound by any theory, the minimal effective concentration of the ACA that is necessary to protect a specific metal surface from corrosion can be determined by:
1) Whatever concentration of the ACA adequately produces an organometallic surface barrier over the metal; or
2) How much residual ACA must remain in solution to ensure that a zero electrical potential exists between the adsorbed organometallic barrier over the metal surface, as well as the molecular organometallic barrier and the surrounding aqueous phase.
Depending on the ionic strength (xcexc) or ion concentration(s) in the surrounding water, including divalent and trivalent metal cations, and the unique electrochemical potential over the surface of a metal, effective ACA concentrations can be customized to meet anti-corrosion performance demands. ACA concentrations in water may range, e.g., from 0.2 to 58 percent by weight depending on where a zero electrochemical potential effect is met between the metal surface and the potentially conductive liquid phase.
One simple method for assessing the adequacy and sufficiency of ACA concentrations, embodied as KHDA, that will effectively control metal oxidation and corrosion in a specific case is described in Example II. In summary, however, a discretionary test matrix of up to 30 aqueous solutions can be prepared, each of which is formulated to produce a solution documented in terms of its specific conductivity (measured in microsiemens (xcexcS)). Where necessary, elementally pedigreed metals designed for anti-corrosion protection are immersed as test specimens in the respective solutions of known specific conductivity. Following two to four weeks of immersion using a desired metal contact temperature, the pedigreed metal samples can be examined for evidence of corrosion using microscopic methods or energy dispersive X-ray analysis.
In the case of energy dispersive X-ray analysis, elemental evidence of oxygen reaction with the surface of the metal is indicative of insufficient ACA effectiveness. Based on the graduated specific conductivity test matrix, some level of specific conductivity will be obvious as a key point above which metal corrosion does not occur. Furthermore, this conductivity will correspond to some minimally effective concentration of a KHDA-based solution that exerts a similar anti-corrosion effect.
The use of any additional ACA concentration beyond that which produces anti-corrosion effects serves only to ensure the functional longevity of the ACA in solution. Once a metal surface, e.g., iron or aluminum, interacts with the ACA, a level of anti-corrosion protection against water vapor and humidity driven corrosion effects is demonstrated. The development and performance of an anti-corrosion barrier effect due to the ACA is described in Example V. Here it has been shown that ferrous metal fibers incorporated into an aqueous plaster-of-Paris formulation (POPF) readily undergo corrosion and rusting during the course of plaster hardening and curing. The use of the aqueous ACA formulation in an identical aqueous plaster formulation, however, halts iron fiber corrosion, rusting and evidence of iron oxide migration through the cured plaster product. The effect of the ACA on the metal fibers persists as a protective anti-corrosion barrier over the iron fibers long after the plaster has cured. Whereas the dry, cured, fiber-impregnated plaster without ACA use shows signs of continued corrosion at relative humidities up to 90 percent, the ACA treated fibers remain shiny and free of rust. This observation further attests to the fact that the ACA appears to work in conjunction with other agents, e.g., in this case, the binding and adhesive agents in the plaster, to form a protective film that may now be dried.
Owing to cost and availability, water is the preferred polar solvent medium for preparing the composition of the invention, when the composition includes those moisture retentive barrier materials miscible with water. Purified, distilled, deionized water at 0.1 xcexcS or tap water can function equally well as aqueous solvents depending on the anti-corrosion applications. The ACA, embodied as KHDA, may also be admixed, colloidally suspended, or homogenized to a size of less than or equal to 2 microns in liquids that may or may not already contain some water but that also display dielectric properties (D-values) substantially lower than that of water alone.
Furthermore, colloid milling or homogenization of the ACA into selected low dielectric solvents will permit formulation of soluble, emulsifiable or colloidal concentrates that can be diluted on demand to meet protective metal anti-corrosion requirements. These products have the consistency of greases or petroleum jelly. Similar embodiments of the ACA can be incorporated within fluids that are designed and engineered to have predictable shear rates and shear stresses. These include non-Newtonian fluids that have Bingham plastic, pseudoplastic, dilatant, thixotropic and rheopexic flow properties as well as systems that exhibit Newtonian behavior.
Alternatively, the ACA may be colloidally stabilized or homogenized, with or without the assistance of surfactants or suspendable solids, into nonpolar liquids such as oils or nonpolar esters of any desirable melting point or description that display high or low D-values. Applications for such an embodiment of the invention are designed to counter the water-mediated corrosive oxidation effects incumbent with fugitive water droplets, condensation or contamination in oils, which mediate the oxidative destruction of engineered metal surfaces. Typical among these applications are those where dielectric transformer or pump oils may be used. The natural water solubility of the ACA ensures that any fugitive water in oils designed and used for their low D-values and/or lubrication will be preempted from having their operative D-values and lubrication properties altered by an unavoidable acquisitions of water
As indicated, water may serve as a singular solvent to demonstrate the favorable anti-corrosion effect of KHDA on metal surfaces, but a variety of water miscible organic solvents with D-values less than that of water can also be useful in augmenting ACA performance. These solvents include primary, secondary and tertiary alcohols, diols, glycols, glycerols, triglycerol ethers, oxygen-based esters, ceramides, sphingolipids, petroleum by-products, alkaline salts of other fatty acids or glycerolphospholipids (e.g., lecithin).
In other cases, the ACA may be encapsulated within liposomes, gels, dextrins or dextrans including cyclodextrins for protracted delivery purposes as the effective ACA is needed. For example, in one preferred model embodiment, dry porous spherical dextran beads can be independently saturated with HDA and alkali, or KHDA alone. Such embodiments of the ACA will provide time release or release on demand anti-corrosion protection to high dielectric fluids as water is accrued by the fluid and water-mediated corrosion of surrounding metal surfaces would ordinarily be promoted.
In another particularly preferred embodiment, a powdered form of the ACA may be admixed with a powdered form of any moisture retentive barrier coating material as described herein for use in powder metallurgy processes for coating metals, which are well known to those of ordinary skill in the art. Such processes provide the anticorrosive coating properties according to the invention for use, e.g., in the automotive, aerospace and tool industries without the necessity of handling large volumes of liquids.
For some desired applications of the ACA, the invention can be implemented in a solution where, e.g., less than 20 percent by weight of the liquid phase is contributed by water, and the balance of the volume is contributed by low dielectric and water miscible solvents. Such water miscible organic embodiments of the ACA may support non-corrosive storage of finely engineered medical instruments or other fine mechanical devices where the desirable antimicrobial effects of alcohol(s) for example, dovetail with the beneficial anticorrosive effects of the ACA. Required concentration levels of the ACA embodied in high dielectric solvents that contain water may be practically determined as presented in Example II. Similar embodiments of the ACA with low water content and water miscible organic solvents also provide a fluid-platform basis, with or without other adjuvants, for controlling metal oxidation.
A chief design and application criterion for implementing the method of the invention is based on the fact that metals, and particularly ferrous metals, are best protected from the perils of oxidation in a dessicated inert gas atmosphere. However, these are unrealistic conditions. Thus, in preferred embodiments, the composition and method of the invention permit a practical extension of this protection by augmenting the ACA performance properties with polymers and other viscous systems.
One preferred and widely applicable embodiment of the invention centers upon using an aqueous ACA solution according to the invention as a solvent for the admixture of polymers that impart predictably-graded degrees of (1) density, (2) molecular weight distribution, (3) viscosity, (4) hygroscopicity, (5) surface tension and (6) lubricity. Such polymers may be purely synthetic, or natural, or mixtures of natural and synthetic polymers, or represent any degree of mixed polar and non-polar properties that meet some use demand. However, incorporated together, such polymers have no innate anti-corrosion capabilities of their own. It is obvious, too, that all six of the properties cited are common performance criteria for petroleum produces and as in cases of water soluble polymers, petroleum-based substances can also be specifically varied in their compositional properties to meet certain use demands. Such adaptability to specific overlapping use applications shared by both water-soluble polymers and petroleum product could occur in many areas but the corrosion issue tied to water-based systems is often satisfactory for making decisive application choices. Although lubricity and viscosity properties of petroleum products can effectively shield ferrous metals from some corrosive reactions, petroleum products are definitely not anti-corrosion agents. Indeed, many petroleum products that temporally shield metals from rusting and oxidation undergo oxidation themselves, which obviates their anti-corrosion protection. The invention permits the admixture of a genuine anti-corrosion agent according to the invention into any fluid or viscous system with or without the contribution of any polymers to inhibit metal oxidation, including that of ferrous metals and aluminum.
Chief among favored water soluble polymers that can embody the invention are those polymers such as polyethylene glycol (PEG), methoxypolyethylene glycol (MPEG), and polyalkylene glycol (PAG) (also described as a linear polymer of propylene and ethylene oxides). The general formula for PEG is Hxe2x80x94[Oxe2x80x94CH2xe2x80x94CH2]nxe2x80x94OH and the corresponding designation for MPEG is CH3xe2x80x94[Oxe2x80x94CH2xe2x80x94CH2]nxe2x80x94OH. For PAGs or the linear copolymers of ethylene and propylene oxides, the general formula corresponds to Xxe2x80x94Oxe2x80x94[CH2xe2x80x94CH(CH3)xe2x80x94O]n[CH2xe2x80x94CH2xe2x80x94O]mxe2x80x94Z where subscripts xe2x80x9cnxe2x80x9d and xe2x80x9cmxe2x80x9d are average numbers of different repeating bracketed monomers namely xe2x80x9cpropylene oxidexe2x80x9d and xe2x80x9cethylene oxide,xe2x80x9d xe2x80x9cXxe2x80x9d is a hydrogen atom (xe2x80x94H) or any other relevant nondiscript functional group and xe2x80x9cZxe2x80x9d is a hydrogen atom (xe2x80x94H) or hydroxyl (xe2x80x94OH) group. Average molecular weights for PEGs, MPEGs and PAGs are less than 100,000 with many in the usual range of less than 15,000. Other favored embodiments of the invention can include addition of the ACA to nonionic, water-soluble poly(ethylene oxide) polymers characterized by high molecular weight ranges from 75,000 to 12,000,000 daltons.
The low concentration level of KHDA or HDA necessary to impart the anti-corrosion effect of the invention to water permits a wide variation in the use and composition of any water-inclusive polymer systems. Thus, water-based polymers according to the invention can have high or low polymer concentrations, high or low amounts of water, with or without hydrophobic components that allow wide ranging lubricity, miscibility, viscosity, solvency, boiling point, flash point, freezing point and in some cases elastomer compatabilities that remain unaffected by the anticorrosive""s presence. These considerations afford possibilities for a variety of low-toxicity petroleum analogue products that are water-based and non-corrosive to ferrous and many non-ferrous based metals. The low toxicity of various glycols that already have (1) food-grade GRAS (generally recognized as safe)-status under U.S. Food and Drug Administration guidelines; or, (2) an acceptable safety status under the aegis of the United States Pharmacopeia (USP)/National Formulary (NF) guidelines for human exposure can now assume new unanticipated application uses with a GRAS-sanctioned and food-grade adjuvant such as KHDA or HDA. Whether or not some or all of these components are food-grade, GRAS or USP/NF sanctioned does not affect the performance of the anti-corrosion effects demonstrated by the invention.
Another preferred embodiment of the invention centers upon admixture of the ACA to homogenous or heterogenous polymers of amino acids including their peptide structures having molecular weights less than 5,000 daltons or unqualified protein structures greater than 5,000 daltons that are synthetically manufactured, biologically produced or genetically engineered by any route. By practical extension, use of the ACA can also be in conjunction with homo- or heteroglycan polymers of any description obtained and crafted by any route. These include ACA addition to hydrocolloidal (1) anionic seaweed polysaccharides such as agar, alginic acid polymers and carrageenan; (2) anionic exudate polysaccharides including arabic, ghatti, karaya and tragacanth gums; (3) non-ionic seed polysaccharides such as guar, locust bean and tamarind; (4) microbiologically or in vitro enzymatically synthesized polyglucans with or without proteins including but not limited to xanthan gum, cranberry extract and other extracts; and (5) any modified carbohydrate polymers such as derivatized celluloses including hydroxyethylated or carboxymethylated starches or celluloses. These embodiments are cited merely as examples and do not limit the intent and spirit of the invention applied to any numbers of polymeric substances that can benefit in use from the invention. Regardless of their USP/NF, GRAS or food-grade status, the performance of the ACA remains consistent and unaffected.
The operational principles of the invention can also be demonstrated in preferred embodiments where graphite or particulated carbon suspensions exist with the food-grade ACA so as to afford a lubricating suspension with anti-corrosion properties. The liquid fraction of the suspension can contain hydrophilic or hydrophobic components as well as various mixtures of any other adjuvants that effect the functionality of the suspension.
This embodiment does not discount the use of other adjuvants that optimize the application of the invention""s concepts such as the addition of antioxidants, chelation agents, surfactants, silica and silicone oils.
Additional concerns regarding issues of environmental waste, persistence and industrial hygiene also challenge the long-term safety and routine clean-up procedures tied to the use of petroleum products. Based on these factors, water-based anti-corrosion formulations of KHDA combined with glycerol, diols, polyethylene glycols as well as water emulsified and stabilized vegetable oils (i.e., water-in-oil emulsions) can offer many advantages of petroleum products. Some of these may or may not require surfactant uses. Typical application venues for such aqueous-based, non-hydrocarbon, but petroleum-like formulations include: lubricants for metalworking, cutting oils, food machinery, grease compositions, metal part protectants (nuts, bolts, etc.), hydraulic fluids, compressor and vacuum pump oils; humectants, iron sequesterants and whiteners in paper processing; metal corrosion inhibition over food processing surfaces; toiletry formulations including adjuncts to shaving cream that ensure anti-corrosion and sharpness on metal blades and cutting edges; nonconductive alternating current transformer fluids and coolants; and many other areas.
Furthermore, the inseparable functional ability of the ACA, embodied as KHDA, to modulate the dielectric constant of water is no less important. This property allows further unexpected applications for the possible control of the specific conductivity of water as it relates to minimizing electrochemically-based metal corrosion over existing metal barrier-coatings or passivated metal surfaces; decreasing oxidative reactions between metal surfaces and biofilms; or reducing electrochemically incited adsorption between organic molecules and electrically charged solids in aqueous systems.
The low acute toxicity, non-carcinogenicity and non-teratogenic properties of the ACA disclosed here support its use as a favorable adjunct to reduce the toxicity and environmental persistence of existing less environmentally favorable ACAs. In other cases, the ACA may be selectively formulated with biocides, e.g., antioxidants, surfactants or chelators, to suit any level of microbiological challenge Beyond this, as KHDA, or HDA, is a GRAS, food-grade substance, human exposure at any stage of the life-cycle does not present any known deleterious threat or serious consequence to human health at practical use levels.
Although this invention has been described in terms of some specific embodiments which are set forth in general as well as considerable detail, it should be understood that such description is by way of illustration only and that the invention is not necessarily limited thereto, since alternative embodiments and operating techniques will become apparent to those skilled in the art in view of the disclosure. Accordingly, modifications are contemplated which can be made without departing from the spirit and intent of the invention as described. The following examples are presented to illustrate the advantages of the present invention and to assist one of ordinary skill in making and using the same. These examples are not intended in any way otherwise to limit the scope of the disclosure.